MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (MITAG) WARNING NR 015// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 19W (MITAG), LOCATED APPROXIMATELY 547 NM SOUTHWEST OF SASEBO, JAPAN, HAS TRACKED NORTHWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES SLIGHT WEAKENING OF CORE CONVECTION WITH THE BULK OF THE CONVECTION DISPLACED OVER THE NORTHERN SEMICIRCLE. HOWEVER, A 301803Z AMSR2 36GHZ IMAGE DEPICTS A WELL-DEFINED MICROWAVE EYE FEATURE WITH TIGHTLY-CURVED SHALLOW BANDING. DESPITE THE SLIGHT WEAKENING TREND, THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T5.0 (90 KNOTS) FROM PGTW AND KNES AND A 301311Z SATCON ESTIMATE OF 99 KNOTS. ADDITIONALLY, A 300938Z SMAP PASS SHOWED PEAK WINDS OF 89 KNOTS (1-MINUTE AVERAGE). OVERALL, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE AMSR2 IMAGE. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG (20-30 KNOTS) SOUTHERLY VERTICAL WIND SHEAR (VWS) OFFSET BY ROBUST POLEWARD OUTFLOW. SST VALUES HAVE DECREASED SLIGHTLY TO 26C. TY 19W IS TRACKING ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. THE WIND RADII HAVE BEEN ADJUSTED BASED ON A DETAILED ANALYSIS OF A RECENT ASCAT IMAGE. B. TY 19W IS FORECAST TO CONTINUE TRACKING NORTHWARD THROUGH TAU 12 BUT SHOULD GRADUALLY TURN NORTH-NORTHEASTWARD TO NORTHEASTWARD THROUGH TAU 48 AS IT ROUNDS THE STR AXIS. TY 19W WILL BEGIN EXTRA- TROPICAL TRANSITION (ETT) NEAR TAU 48 AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE. THE SYSTEM SHOULD WEAKEN RAPIDLY AFTER TAU 24 DUE TO INCREASING VWS, COOLER SST AND INTERACTION WITH LAND. AFTER TAU 60, 19W WILL TRACK OVER THE SEA OF JAPAN AND WILL COMPLETE ETT NEAR TAU 72 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN STRONG MIDLATITUDE WESTERLY FLOW. SST VALUES WILL DECREASE TO LESS THAN 24C, WHICH WILL FURTHER AID IN WEAKENING THE SYSTEM. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH A 70NM SPREAD IN SOLUTIONS AT TAU 48, THEREFORE, THERE IS HIGH CONFIDENCE (LOW UNCERTAINTY) IN THE JTWC FORECAST TRACK THROUGH TAU 72. C. AFTER TAU 72, THIS COLD-CORE EXTRA-TROPICAL LOW WILL ACCELERATE EAST-NORTHEASTWARD OVER NORTHERN HONSHU. THE SYSTEM IS STILL EXPECTED TO MAINTAIN GALE-FORCE WINDS. DUE TO THE BROAD NATURE OF THIS LOW AND THE LARGE SPREAD IN THE NUMERICAL MODELS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN